Παρασκευή 22 Ιουλίου 2016

Impaired Vestibular Function and Low Bone Mineral Density: Data from the Baltimore Longitudinal Study of Aging

Abstract

Animal studies have demonstrated that experimentally induced vestibular ablation leads to a decrease in bone mineral density, through mechanisms mediated by the sympathetic nervous system. Loss of bone mineral density is a common and potentially morbid condition that occurs with aging, and we sought to investigate whether vestibular loss is associated with low bone mineral density in older adults. We evaluated this question in a cross-sectional analysis of data from the Baltimore Longitudinal Study of Aging (BLSA), a large, prospective cohort study managed by the National Institute on Aging (N = 389). Vestibular function was assessed with cervical vestibular evoked myogenic potentials (cVEMPs), a measure of saccular function. Bone mineral density was assessed using dual-energy X-ray absorptiometry (DEXA). In two-way t test analysis, we observed that individuals with reduced vestibular physiologic function had significantly lower bone mineral density. In adjusted multivariate linear regression analyses, we observed that older individuals with reduced vestibular physiologic function had significantly lower bone mineral density, specifically in weight-bearing hip and lower extremity bones. These results suggest that the vestibular system may contribute to bone homeostasis in older adults, notably of the weight-bearing hip bones at greatest risk of osteoporotic fracture. Further longitudinal analysis of vestibular function and bone mineral density in humans is needed to characterize this relationship and investigate the potential confounding effect of physical activity.



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Tonal noise of a controlled-diffusion airfoil at low angle of attack and Reynolds number

The acoustic signature of a controlled-diffusion airfoil immersed in a flow is experimentally characterized. Acoustic measurements have been carried out in an anechoic open-jet-wind-tunnel for low Reynolds numbers (from 5 × 104 to 4.3 × 105) and several angles of attack. As with the NACA0012, the acoustic spectrum is dominated by discrete tones. These tonal behaviors are divided into three different regimes. The first one is characterized by a dominant primary tone which is steady over time, surrounded by secondary peaks. The second consists of two unsteady primary tones associated with secondary peaks and the third consists of a hump dominated by several small peaks. A wavelet study allows one to identify an amplitude modulation of the acoustic signal mainly for the unsteady tonal regime. This amplitude modulation is equal to the frequency interval between two successive tones. Finally, a bispectral analysis explains the presence of tones at higher frequencies.



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Internal and contextual cues to tone perception in Medʉmba

This study presents results of an identification experiment with speakers of Medʉmba, a Grassfields Bantu language, aimed at evaluating the relative effects of f 0 and duration in cuing tonal contrasts, as well as the role of lexical vs non-speech pitch contexts in biasing tone perception. Results show that duration is a cue for tone perception, with the influence of duration strongest where target f 0 values were lower. Lexical tone perception is also sensitive to the identity of a preceding lexical tone, but not to the presence of a preceding non-speech pure tone.



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Biomechanical changes associated with femoral derotational osteotomy

Publication date: September 2016
Source:Gait & Posture, Volume 49
Author(s): Bruce A. MacWilliams, Mark L. McMulkin, Roy B. Davis, David E. Westberry, Glen O. Baird, Peter M. Stevens
Torsional deformities of the femur in children may occur as a result of either idiopathic or neuromuscular disorders and may be corrected with derotational osteotomies. Regardless of the underlying etiology, neither the effects of the torsional pathologies nor the alterations resulting from corrective osteotomies are well understood. A study of children with isolated femoral anteversion undergoing a single corrective procedure may assist in understanding the biomechanics of the pathology and the efficacy of surgical correction. A multicenter retrospective study included 25 subjects with idiopathic femoral anteversion who underwent femoral derotational osteotomy and had completed pre and postoperative gait analyses. Both changes with surgery and comparisons to typically developing controls were analyzed. Reduced gait pathology and expected improvements in hip rotation and foot progression were found with derotational osteotomy. Overall gait pathology and pathological differences in pelvic tilt, hip flexion moment and knee adduction moment were found comparing anteversion subjects with typically developing subjects. Following surgery, only hip rotation was significantly and clinically different from typically developing subjects, changing from relatively inward to outward. Idiopathic femoral anteversion creates multifaceted and significant alterations to normal gait and should not be considered solely a cosmetic issue. Additionally, the efficacy of derotational osteotomy is illustrated and may be more broadly applied to other conditions where pathologic femoral anteversion is present.



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Utilization and Efficacy of Computational Gait Analysis for Hamstring Lengthening Surgery

Publication date: Available online 20 July 2016
Source:Gait & Posture
Author(s): Bruce A. MacWilliams, Alan K. Stotts, Kristen L. Carroll, Jacques L. D’Astous
A retrospective analysis of computational gait studies performed in a single lab over a 12year period was undertaken to characterize how recommendations to perform or not to perform hamstring lengthenings were utilized by physicians and the effect on outcomes. 131 subjects were identified as either having hamstring lengthening considered by the referring surgeon, recommended by gait analysis data, or performed. A subset of this data meeting inclusion criteria for pre- and post-surgical timeframes, and bilateral diagnosis was further analyzed to assess the efficacy of the recommendations. There was initial agreement between planned procedures and recommended procedures in just 41% of the cases. Including the cases where there was agreement, gait analysis altered the initial procedure in 54%. In the cases where the initial plan was not supported by gait data, surgeons followed gait recommendations in 77%. In subjects who underwent hamstring lengthening, when surgeons followed or agreed with gait recommendations, patients were 3.6 times more likely to experience a positive outcome.



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Biomechanical changes associated with femoral derotational osteotomy

Publication date: September 2016
Source:Gait & Posture, Volume 49
Author(s): Bruce A. MacWilliams, Mark L. McMulkin, Roy B. Davis, David E. Westberry, Glen O. Baird, Peter M. Stevens
Torsional deformities of the femur in children may occur as a result of either idiopathic or neuromuscular disorders and may be corrected with derotational osteotomies. Regardless of the underlying etiology, neither the effects of the torsional pathologies nor the alterations resulting from corrective osteotomies are well understood. A study of children with isolated femoral anteversion undergoing a single corrective procedure may assist in understanding the biomechanics of the pathology and the efficacy of surgical correction. A multicenter retrospective study included 25 subjects with idiopathic femoral anteversion who underwent femoral derotational osteotomy and had completed pre and postoperative gait analyses. Both changes with surgery and comparisons to typically developing controls were analyzed. Reduced gait pathology and expected improvements in hip rotation and foot progression were found with derotational osteotomy. Overall gait pathology and pathological differences in pelvic tilt, hip flexion moment and knee adduction moment were found comparing anteversion subjects with typically developing subjects. Following surgery, only hip rotation was significantly and clinically different from typically developing subjects, changing from relatively inward to outward. Idiopathic femoral anteversion creates multifaceted and significant alterations to normal gait and should not be considered solely a cosmetic issue. Additionally, the efficacy of derotational osteotomy is illustrated and may be more broadly applied to other conditions where pathologic femoral anteversion is present.



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Utilization and Efficacy of Computational Gait Analysis for Hamstring Lengthening Surgery

Publication date: Available online 20 July 2016
Source:Gait & Posture
Author(s): Bruce A. MacWilliams, Alan K. Stotts, Kristen L. Carroll, Jacques L. D’Astous
A retrospective analysis of computational gait studies performed in a single lab over a 12year period was undertaken to characterize how recommendations to perform or not to perform hamstring lengthenings were utilized by physicians and the effect on outcomes. 131 subjects were identified as either having hamstring lengthening considered by the referring surgeon, recommended by gait analysis data, or performed. A subset of this data meeting inclusion criteria for pre- and post-surgical timeframes, and bilateral diagnosis was further analyzed to assess the efficacy of the recommendations. There was initial agreement between planned procedures and recommended procedures in just 41% of the cases. Including the cases where there was agreement, gait analysis altered the initial procedure in 54%. In the cases where the initial plan was not supported by gait data, surgeons followed gait recommendations in 77%. In subjects who underwent hamstring lengthening, when surgeons followed or agreed with gait recommendations, patients were 3.6 times more likely to experience a positive outcome.



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Biomechanical changes associated with femoral derotational osteotomy

Publication date: September 2016
Source:Gait & Posture, Volume 49
Author(s): Bruce A. MacWilliams, Mark L. McMulkin, Roy B. Davis, David E. Westberry, Glen O. Baird, Peter M. Stevens
Torsional deformities of the femur in children may occur as a result of either idiopathic or neuromuscular disorders and may be corrected with derotational osteotomies. Regardless of the underlying etiology, neither the effects of the torsional pathologies nor the alterations resulting from corrective osteotomies are well understood. A study of children with isolated femoral anteversion undergoing a single corrective procedure may assist in understanding the biomechanics of the pathology and the efficacy of surgical correction. A multicenter retrospective study included 25 subjects with idiopathic femoral anteversion who underwent femoral derotational osteotomy and had completed pre and postoperative gait analyses. Both changes with surgery and comparisons to typically developing controls were analyzed. Reduced gait pathology and expected improvements in hip rotation and foot progression were found with derotational osteotomy. Overall gait pathology and pathological differences in pelvic tilt, hip flexion moment and knee adduction moment were found comparing anteversion subjects with typically developing subjects. Following surgery, only hip rotation was significantly and clinically different from typically developing subjects, changing from relatively inward to outward. Idiopathic femoral anteversion creates multifaceted and significant alterations to normal gait and should not be considered solely a cosmetic issue. Additionally, the efficacy of derotational osteotomy is illustrated and may be more broadly applied to other conditions where pathologic femoral anteversion is present.



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Utilization and Efficacy of Computational Gait Analysis for Hamstring Lengthening Surgery

Publication date: Available online 20 July 2016
Source:Gait & Posture
Author(s): Bruce A. MacWilliams, Alan K. Stotts, Kristen L. Carroll, Jacques L. D’Astous
A retrospective analysis of computational gait studies performed in a single lab over a 12year period was undertaken to characterize how recommendations to perform or not to perform hamstring lengthenings were utilized by physicians and the effect on outcomes. 131 subjects were identified as either having hamstring lengthening considered by the referring surgeon, recommended by gait analysis data, or performed. A subset of this data meeting inclusion criteria for pre- and post-surgical timeframes, and bilateral diagnosis was further analyzed to assess the efficacy of the recommendations. There was initial agreement between planned procedures and recommended procedures in just 41% of the cases. Including the cases where there was agreement, gait analysis altered the initial procedure in 54%. In the cases where the initial plan was not supported by gait data, surgeons followed gait recommendations in 77%. In subjects who underwent hamstring lengthening, when surgeons followed or agreed with gait recommendations, patients were 3.6 times more likely to experience a positive outcome.



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Effects of Age and Implanted Ear on Speech Recognition in Adults with Unilateral Cochlear Implants

The objective of this study was to examine how age and implanted ear contribute to functional outcomes with cochlear implantation (CI). A retrospective review was performed on 96 adults who underwent unilateral CI. Older adults with right-ear implants had higher Hearing in Noise Test (HINT) scores at 1 year by 10.3% (p = 0.06). When adjusted to rationalized arcsine units (rau), right-ear HINT scores in older adults were higher by 12.1 rau (p = 0.04). Older adults had an 8.9% advantage on the right side compared to the left in post- versus preimplant scores for consonant-vowel nucleus-consonant words (p = 0.05). No significant differences were observed for younger adults. In conclusion, although adults of all ages experience improvements in speech perception following CI, there might be a subtle but consistent right-ear advantage in older adults.
Audiol Neurotol 2016;21:223-230

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Speech-evoked activation in adult temporal cortex measured using functional near-infrared spectroscopy (fNIRS): are the measurements reliable?

Publication date: Available online 20 July 2016
Source:Hearing Research
Author(s): Ian M. Wiggins, Carly A. Anderson, Pádraig T. Kitterick, Douglas EH. Hartley
Functional near-infrared spectroscopy (fNIRS) is a silent, non-invasive neuroimaging technique that is potentially well suited to auditory research. However, the reliability of auditory-evoked activation measured using fNIRS is largely unknown. The present study investigated the test-retest reliability of speech-evoked fNIRS responses in normally-hearing adults. Seventeen participants underwent fNIRS imaging in two sessions separated by three months. In a block design, participants were presented with auditory speech, visual speech (silent speechreading), and audiovisual speech conditions. Optode arrays were placed bilaterally over the temporal lobes, targeting auditory brain regions. A range of established metrics was used to quantify the reproducibility of cortical activation patterns, as well as the amplitude and time course of the haemodynamic response within predefined regions of interest. The use of a signal processing algorithm designed to reduce the influence of systemic physiological signals was found to be crucial to achieving reliable detection of significant activation at the group level. For auditory speech (with or without visual cues), reliability was good to excellent at the group level, but highly variable among individuals. Temporal-lobe activation in response to visual speech was less reliable, especially in the right hemisphere. Consistent with previous reports, fNIRS reliability was improved by averaging across a small number of channels overlying a cortical region of interest. Overall, the present results confirm that fNIRS can measure speech-evoked auditory responses in adults that are highly reliable at the group level, and indicate that signal processing to reduce physiological noise may substantially improve the reliability of fNIRS measurements.



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Speech-evoked activation in adult temporal cortex measured using functional near-infrared spectroscopy (fNIRS): are the measurements reliable?

Publication date: Available online 20 July 2016
Source:Hearing Research
Author(s): Ian M. Wiggins, Carly A. Anderson, Pádraig T. Kitterick, Douglas EH. Hartley
Functional near-infrared spectroscopy (fNIRS) is a silent, non-invasive neuroimaging technique that is potentially well suited to auditory research. However, the reliability of auditory-evoked activation measured using fNIRS is largely unknown. The present study investigated the test-retest reliability of speech-evoked fNIRS responses in normally-hearing adults. Seventeen participants underwent fNIRS imaging in two sessions separated by three months. In a block design, participants were presented with auditory speech, visual speech (silent speechreading), and audiovisual speech conditions. Optode arrays were placed bilaterally over the temporal lobes, targeting auditory brain regions. A range of established metrics was used to quantify the reproducibility of cortical activation patterns, as well as the amplitude and time course of the haemodynamic response within predefined regions of interest. The use of a signal processing algorithm designed to reduce the influence of systemic physiological signals was found to be crucial to achieving reliable detection of significant activation at the group level. For auditory speech (with or without visual cues), reliability was good to excellent at the group level, but highly variable among individuals. Temporal-lobe activation in response to visual speech was less reliable, especially in the right hemisphere. Consistent with previous reports, fNIRS reliability was improved by averaging across a small number of channels overlying a cortical region of interest. Overall, the present results confirm that fNIRS can measure speech-evoked auditory responses in adults that are highly reliable at the group level, and indicate that signal processing to reduce physiological noise may substantially improve the reliability of fNIRS measurements.



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Speech-evoked activation in adult temporal cortex measured using functional near-infrared spectroscopy (fNIRS): are the measurements reliable?

Publication date: Available online 20 July 2016
Source:Hearing Research
Author(s): Ian M. Wiggins, Carly A. Anderson, Pádraig T. Kitterick, Douglas EH. Hartley
Functional near-infrared spectroscopy (fNIRS) is a silent, non-invasive neuroimaging technique that is potentially well suited to auditory research. However, the reliability of auditory-evoked activation measured using fNIRS is largely unknown. The present study investigated the test-retest reliability of speech-evoked fNIRS responses in normally-hearing adults. Seventeen participants underwent fNIRS imaging in two sessions separated by three months. In a block design, participants were presented with auditory speech, visual speech (silent speechreading), and audiovisual speech conditions. Optode arrays were placed bilaterally over the temporal lobes, targeting auditory brain regions. A range of established metrics was used to quantify the reproducibility of cortical activation patterns, as well as the amplitude and time course of the haemodynamic response within predefined regions of interest. The use of a signal processing algorithm designed to reduce the influence of systemic physiological signals was found to be crucial to achieving reliable detection of significant activation at the group level. For auditory speech (with or without visual cues), reliability was good to excellent at the group level, but highly variable among individuals. Temporal-lobe activation in response to visual speech was less reliable, especially in the right hemisphere. Consistent with previous reports, fNIRS reliability was improved by averaging across a small number of channels overlying a cortical region of interest. Overall, the present results confirm that fNIRS can measure speech-evoked auditory responses in adults that are highly reliable at the group level, and indicate that signal processing to reduce physiological noise may substantially improve the reliability of fNIRS measurements.



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Speech-evoked activation in adult temporal cortex measured using functional near-infrared spectroscopy (fNIRS): are the measurements reliable?

Publication date: Available online 20 July 2016
Source:Hearing Research
Author(s): Ian M. Wiggins, Carly A. Anderson, Pádraig T. Kitterick, Douglas EH. Hartley
Functional near-infrared spectroscopy (fNIRS) is a silent, non-invasive neuroimaging technique that is potentially well suited to auditory research. However, the reliability of auditory-evoked activation measured using fNIRS is largely unknown. The present study investigated the test-retest reliability of speech-evoked fNIRS responses in normally-hearing adults. Seventeen participants underwent fNIRS imaging in two sessions separated by three months. In a block design, participants were presented with auditory speech, visual speech (silent speechreading), and audiovisual speech conditions. Optode arrays were placed bilaterally over the temporal lobes, targeting auditory brain regions. A range of established metrics was used to quantify the reproducibility of cortical activation patterns, as well as the amplitude and time course of the haemodynamic response within predefined regions of interest. The use of a signal processing algorithm designed to reduce the influence of systemic physiological signals was found to be crucial to achieving reliable detection of significant activation at the group level. For auditory speech (with or without visual cues), reliability was good to excellent at the group level, but highly variable among individuals. Temporal-lobe activation in response to visual speech was less reliable, especially in the right hemisphere. Consistent with previous reports, fNIRS reliability was improved by averaging across a small number of channels overlying a cortical region of interest. Overall, the present results confirm that fNIRS can measure speech-evoked auditory responses in adults that are highly reliable at the group level, and indicate that signal processing to reduce physiological noise may substantially improve the reliability of fNIRS measurements.



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Speech-evoked activation in adult temporal cortex measured using functional near-infrared spectroscopy (fNIRS): are the measurements reliable?

Publication date: Available online 20 July 2016
Source:Hearing Research
Author(s): Ian M. Wiggins, Carly A. Anderson, Pádraig T. Kitterick, Douglas EH. Hartley
Functional near-infrared spectroscopy (fNIRS) is a silent, non-invasive neuroimaging technique that is potentially well suited to auditory research. However, the reliability of auditory-evoked activation measured using fNIRS is largely unknown. The present study investigated the test-retest reliability of speech-evoked fNIRS responses in normally-hearing adults. Seventeen participants underwent fNIRS imaging in two sessions separated by three months. In a block design, participants were presented with auditory speech, visual speech (silent speechreading), and audiovisual speech conditions. Optode arrays were placed bilaterally over the temporal lobes, targeting auditory brain regions. A range of established metrics was used to quantify the reproducibility of cortical activation patterns, as well as the amplitude and time course of the haemodynamic response within predefined regions of interest. The use of a signal processing algorithm designed to reduce the influence of systemic physiological signals was found to be crucial to achieving reliable detection of significant activation at the group level. For auditory speech (with or without visual cues), reliability was good to excellent at the group level, but highly variable among individuals. Temporal-lobe activation in response to visual speech was less reliable, especially in the right hemisphere. Consistent with previous reports, fNIRS reliability was improved by averaging across a small number of channels overlying a cortical region of interest. Overall, the present results confirm that fNIRS can measure speech-evoked auditory responses in adults that are highly reliable at the group level, and indicate that signal processing to reduce physiological noise may substantially improve the reliability of fNIRS measurements.



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